X-ray tube



G. 'c. KUCH'AER X-RAY TUBE Filed Feb. 9, 1924 Fig. 1.

Fig.5.

' Patented Dec. 14, 1926.

UNITED STATES PA rENT' ,.oFF1cE..,

GEORG coimnp Kuonnn, on vI nnNA, nus'rnm, Assrcnon- To run rim: rriomx RonrGnNRonnnN-rABnIK N, or RUDOLSTADT, GERMANY.

x-n-AY TUB/E.

Application filed February 9, 1924, Serial No. 691,844, and in Germany February 16, 1 923. i

In order to obtain sharp X-ray projections surface of the anticathodeupon which the T cathode rays impinge, is ofsmall area, say

.only one and a half. to three millimetres in diameter. 3 Such precision focussing is possible in screen examinations since for this purpose thecurrent strength of the electric discharge through the X-ray tube need not exceed three to eight milli-amperes.

But if it were attempted to make Xrray photographs with such a precision tube the comparatively large discharge current neces-.

saryfor this purpose would overload the small focal spot on the target and the tube would be destroyed. There is a hitherto unsatisfied demand for X-ray tubes which can be used either for exact screen-examinations or for making photographic exposures with a discharge current of up to one hundred milli-amperes. i

.The present invention relates to an incan descent cathode X-ray tube designed to fill this need. l

Certain forms of construction of Rontgen tubes embodying the invention, in some cases witha diagram of their connections, are illustrated diagrammatically in the accompanying drawings wherein Figure 1 is a diagrammatic view of one form of the invention; Figure 2 ,is a similar view of a slightly difi'erent form; and Figure's'3, 4 and which the X-ray tube is. to "be used and so i is rendered active. To make one source of heatmg current serve for both cathodes g and h a switch 71 may be provided, as shown in Figure 2, by

, -;which either of the cathodes mayfbe connected with a'source f of hcating current.

It is not necessary that each incandescent cathode should have its own concentrating device is. Instead two or more spiral incandescent w res m and a may be arranged wlthm a s ngle concentrating device 0 (Fig ure'S) in such fashion that the cathode rays from one or more incandescent. wires pass besideone or more other incandescent wires; an alternative const notion with helical incandescent wires is s own 'iIi Figure 4:.

Further, parts of one and the same incandescent wire maybe used as the two or more cathodes, the current connections p for the several cathodes being connected to different parts of one and the same incandescent wire 1" as shown in Figure 5.

The'high vacuum wich only permits passage of current on account of the cathode being made incandescent causes the cathode 5 are views of difierent forms of, concentrating devices employed.

- Figure ll'shows a highly evacuated bulb cision purposes, i. e. it is so formedthat the] rays directed by .it upon the anticathode a are focussed upon'a small area. Theother j incandescent cathode 0,;the heavy load oath ode, on the contrary 'focusses its projected.

rays upon an area of the anti-cathode markedly larger than the first-harriedarea so that the anode is not unduly overloaded even by the maximum discharge current. ca tliode b or cathode a is supplied with Either g 5 heating current according to thepurpose for 4..An X -ray device comprising I ray emission to be confined to the filament which is for the time being incandescent.

What I claim is:

1. In an X-ray device, a highly evacuated envelope, an anode'therein, two or more cathindependently from-one another, and means for focusing a discharge from the said cathodes respectively. on areas of markedly different-size on the surface of the anode.

2: In an X-ray device, a highly evacuated envelope an anode therein, two or more cathodes adapted-to be heatedto incandescence independently from one, another, and means for focusing a discharge from each cathode to the exclusion of the other on areas of markedly diiferent sizes on the sur-' face of said anode.

3. An X-ray device comprising the combination of an envelope the space within which is highly evacuated, an anode. two .or g 4 more cathodes adapted'to be heated to illcandescence, means for focusing a discharge from the said cathodes respectively on areas of:-markedly= different size on the surface of the. anode, and means for supplyingleach the cathodesfrom a separate source iofihea" ing current respectively.

bination of an envelope the space within which is highly evacuated, an anode, two or more cathodes adapted to be heated to incande'scence, means for focusing a discharge from the said cathodes respectively on areas of markedly diiferent size on the surface of the anode, a common source of heating current, and means for connecting the same alternately to any one or the other of the said.

cathodes.

5. In an X-ray device, an envelope the space witlnn wh ch is hlghly evacuated, an

anode, two or more cathodes adapted to be heated to incandescence independently from one another, a cathode including one or more cathode filaments, the conductors of the heating current supply joining one 'andthe same cuthode at different points, thus dividing the cathode filament in a number of portions each of which may be heated independently from the others.

In witness whereof I have hereunto set my hand this 15th day of January, 1924.

GEORG CONRAD KUCHER. 

